Chromiferous azo-dyestuff and process of making same



Patented Aug. 27, 1935 g I omen-- ACHROMIFEROUS Azomrri's'rurr' AND rnoonss OF MAKING SAME Fritz Straub, Basel, and Hermann Schneider, \Riehen, near Basel, Switzerland, ."assignors to Society of Chemical Industry in lBasle, Basel,

Switzerland 'NWDraWing. Application March 19, 1934, Serial No. "716,427. "InSwitzcrland March 31, 1933 1'8Claims. (613260-12) v This invention relates tothe manufacture of chromiferous azo-dyestufis from mixtures of chromed and chromable azo-dyestufis which mixtures contain at least one dyestuff of the general formula wherein the hydroxyl-and the azo-group are in orthoeposition .to eachaother and wherein n equals 1 :to 3 and Requals a naphthol radicalby heating the mixture inan aqueous medium with an alkali-forming metal salt which, in .aqueous solution, is at the .most slightly hydrolyzed. V The mixture of chromed-andchromable dyestuffs to be used in this invention as the :parent material must merely fulfill the condition that it contains a dyestufl" "of the above general formula which may or may znot contain chromium which; further, may be present as a mixed chromium compound with ,any other azo-dyestuff and may, for example, be obtained from diazotized l-amino 2 hydroxynaphthalene 4 sulfonic acid or 2-amino-l-hydroxynaphthalene- 4 sulfonic acid or :from 2-amino-11-hydroxynaphthalene-4,8 -disulfonic acid or Z-amino-l-hydroxynaphthalene-4,6-disulfonic acid by coupling the acid-with lor 2-hydroxynaphthalenes and the substitution products thereof, such as chl orohydroxyn aphthalenes, fbromohydroxynaphthalenes, methylhydroxynaphthalenes and alkoxyhydroxynaphthalenes. In addition the mixture may contain various chromed and chromable mono-, disor poly-azo-dyestufis; thesd may be obtained, for example, from diazotized aromatic amines of the benzene or naphthalene series and any coupling components, for example arylamines, phenols or compounds in which the carbon atorn'ca-pable of coupling belongs to a heterocycle ring or to an open chain; coupling components of which the coupling carbon atom belongs to a heterocyclic ring are, for example, pyrazolones, hydroxyquinolines and barbituric acids,lwhe reas acetoacetic acid derivatives and benzoyl acetic orthocarboxylic acids are coupling components, the coupling carbon atom of which belongs to an open chain,

The chromed 'azo-dyestufis which are contained in the mixture may be produced by chroming the azo-dyestufi by various known methods and with various chroming agents such processes. are, t examp eichrom e brimea s 1 agents which, yieldchromium in acid, neutral or alkaline medium :intanwopen vesselor underrpressure,-.-in presence v.or absence of l .a suitable additionisuch as,. for-.example, an inorganic or an organic acid, or a soluble-salt thereof, or another ":45 substance such as an-organic solvent.

The mixture :to be used for. the process may contain. only :onechromed azo-dyestufiandenly one chromable a-zo-dyestufi orionly one chromed azo-dyestuff and two or more chromable -azol0 :dyestufis or two or rmore chromed azo-dyestuffs and only one chromable azo-dyestuif, or two or more chromed azo-dyestuffs and two or more chromable azo-dyestufis.

Furthermore :the rchromed -azo-dyestufis in the is mixture may be derived from the same, chrom able azo-dyestufis present-in the =mixturezor they :may be different :from these chromable dyestuffs, The proportion of :the'ohromed am-dyestuffs to the chromable azo-dy'estuffs in the mixture 20 may vary within wide limits; moreover, there may be used for the1process=a-mixture which has 'been obtained n'otwfrom isolated chromed dyestufis but :by using :chromin'g solutions or -suspen sions which; if desired, :may be neutralized.

Theamixture of chromed and'chromable 'azodyestuffs may'ybe heated in an aqueous medium which, I in addition to water, may contain an on ganic SOIVBIItOIiSUSDGIISiOII agent which t-is misciblewith water,for-example, an'alcohol, in addi- 3Q tionto alkali-forming metal salt such as "the sodium, potassium or ammonium/saltjof an inorganic, aliphatic or aromatic :acid which is at the most feebly hydrolyzed inaqueous solution and :theiheating may occur-in an open vessel or under pressure or eveninrthe' dye ibath. Alkaliforming metal salts which are at the most feebly hydrolyzed in aqueous solution are for example sodium chloride, sodium and potassium sulfates, sodiumi'acetate, :sodium formate, sodium s-ben- 0: zene :sulfonate, :sodium naphthalene 'sulfonates, ammonium sulfate, magnesiumrsulfate, ammonium'zacetateand sodium benzoate. I 1

Particularly valuable dyestuffs -=are produced when :achromium-compound of the dyestuff of the aforesaid general formula is used and 'thesaid dyestufi in unchromed condition, for in this manner dyestuffs dyeing navy blue are obtained which, as contrasted the dyestuffs of this group hitherto known as dyeing similar tints, are un iform in dyeing deep tints and are fast in every respect. 7 v

The chromium compounds obtainable by the in' vention are-characterized by very good solubility water suitable for dyeing animal fibres and hours in a reflux apparatus.

Example 1 41.6 parts of the azo-dyestuff of the formula OH HO- SOaH from diazotized 1-amino-2-hydroxynaphthalene- 4-sulfonic acid and 2-hydroxynaphthalene are mixed in aqueous solution with a quantity of -chromium formate corresponding with 8 parts of CrzOs and the mixture is heated to boiling for '10-12 hours in a reflux apparatus while stirring.

The filtered chromium compound of the dyestuff is suspended in '800 parts of Water and there are added 20.8 parts of the azo-dyestuff from diazotized 1 amino-2-hydroxynaphthalene-4-sulfonic' acid and 2 hydroxynaphthalene together with 20 parts of calcined sodium sulfate while stirring and the whole is then boiled for 12-15 The mass which, for the greater-part, remains undissolved is now dissolved by adding parts of caustic soda lye of 30 percent strength and the chromed dyestuff is separated byaddition of common salt and neutralization with hydrochloric acid of 10 per cent strength. It is filtered and dried. It dyes wool in a bath acid with an organic acid and sulfuric acid navy blue tints of very good fastness, particularly good fastness to rubbing, and excellent color in the artificial light.

A chromiferous dyestuff with similar dyeing properties is obtained by treating the chromed dyestuff from diazotized l-amino-2-hydroxynaphthalene-4-sulfonic acid and l-hydroxynaphthalene with the unchromed'azo-dyestuff from diazotized 1-amino-2-hydroxynaphthalene- 4-su1fonic acid and l-hydroxynaphthalene, or the chromed dyestuff from diazotized 1-amino-2- hydroxynaphthalene-l-sulfonic acid and. 2-hydroxynaphthalene with the unchromed azo-dyestuff from diazotized l-amino-2-hydroxynaphthalenel-sulfonic acid and l-hydroxynaphthalene in the manner described in the second paragraph of this example.

' I Example 2 The separated chromed dyestuif, obtained by boiling for 12 hours a mixture of 41.6 parts of the az'o-dyestufi from diazotized l-amino-Z- hydroxynaphthalen-=4-sulfonic ,acid and 2-hydroxynaphthalene witha chromium 'formate solution-corresponding with'8 parts of- CizOs, is

stirred in the form of a moist paste with 41.6,

is filtered and the filtrate is evaporated to dryness in a vacuum on the water bath,

The new chromium compound dissolves very easily in water to a blackish blue solu on and dyes wool in a bath acid with organic acid and sulfuric acid navy blue tints of very good fastness.

Example 3 30 parts of a chromium compound obtained in alkaline medium of the dyestuff of the formula V OH mm dia zotized 1-amino-2-hydroxynaphthalenel-sulfonic acid and l-hydroxynaphthalene,which compound contains'one atom of chromium for one molecule of the dyestufi, are dissolved in .600 parts of hot Water together with '7 .5 parts of the azo-dye'stuff of the formula H03? 7 on 1 from diazotized 2-amino-l-hydroxynaphthalene- 4,8-disulf0nic acid and 2-hydroxynaphthalene. There are added 7 parts of calcined sodium sulfate and boiling is continuedfor a long time in a reflux apparatus. The blue solution of the new chromium compound thus obtained'is filtered 3 and the filtrate evaporated to dryness on the water bath in a vacuum; the chromium compoundis a violetish black powder soluble in water to a blue solution in' caustic soda lye of 10 per cent strength to a violet solution and in concentrated sulfuric acid to a blackish blue-green solution. The new chromiferous dyestuif dyes wool and silk in an acid bath blue tints of excellent properties of fastness.

from diazotized 1-amino-2-hydroxynaphthalene- 4-sulfonic acid and l-hydroxynaphthalene are dissolved in 1200 parts of hot water together with 12 parts of the dyestufi of the formula 6-nitro-2-ami'no-1-phenol-4- There are added 20 parts of crystallized sodium acetate and the whole is boiled for a long time in from diazotized sulfonic acid and 2-hydroxynaphthalene.

a reflux apparatus. After filtering the blackish blue solution to '-separate small quantities of A solution containing 30.3 parts of a chromium compound produced in alkaline medium of the dyestuff of the formula $0311 from diazotized 1-amino-2-hydroi;ynaphthalene- 4-sulfonic acid and l-hydroxynaphthalene, 19.1 parts of the dyestufi of the formula from diazotized 1-amino-2-hydroxynaphthalene I i-sulfonic acid and 1-phenyl-3-methyI-5-pyrazclone and 11.9 parts of sodium benzoatein 1000 parts of water is heated in a pressure vessel for 4 hours at l20-125 C. After cooling the new chromiferous dyestuif is completely dissolved by addition of caustic soda lye, thesolution is filtered from impurities and the filtrate is neutralizedwith dilute acid and evaporated to dryness in a vacuum. The dyestufi thus obtained is a black powder which dissolves in. water, dilute sodium carbonate solution and dilute caustic soda lye to violet solutions and in concentrated sulfuric acid to brown-violet-black solutions. It dyes wool in a bath acid with organic acid and sulfuric acid brown-violet tints. l

Example 6 In, 400. parts of .water there are-dissolved 353 parts of the chromiferous dyestufl whichhas been obtained by chroming in common in acid medium equal parts: of the dyestufi from diazotized l-aminc-2-hydroxynaphthalene-4-sulfonic acid andr'2 hydroxynaphthalene and the dyestuff from diazotized 1-amino-2-hydroxynaphthalene-4-sulfonic acid and l-hydroxynaphthalene together with 11.1 parts of -sodium tormate; this solution is heated for several hours together with the solution of 15.4 parts of the dyestuff from nitrated 1 diazo 2-hydroxynaphthalene-4sulfonic acid and 2-hydroxynaphthalene in 460 parts of water, the evaporated water being made good....The whole is now cooled to 40-45 C. and the new chromiferousdyestuif is completely-dissolved byaddition of caustic soda lye and the solution filtered from impurities. The filtrate is neutralized with. dilute acid and evaporated to dryness in avacblack powder of bronze appearance whichdissolves in water and in dilute sodium carbonate solution to a blackish blue-violet solution, indilute caustic soda lye to a blackish red-violet solution and in concentratedsulfuric acid to a black- Example I In 200 parts of Water there are dissolved 14.6 parts of the chromiferous dyestuif, obtained by chroming in common in an acid medium equal parts ofthe dyestufi from diazotized l-amino-2- hydroxynaphthalene-4-sulfonic acid and 2-hydroxynaphthalene and the dyestu'fi from diazotized 1-amino-2-hydroxynaphthalene-4-sulfonic acid and l-hydroxynaphthalenc, and 4.8 parts of sodium benzene sulfonate. This solution is heated for several hours with a'solution of 10.3 parts of the dyestufi from nitrated l-diazo-Z-hydroxynaphthalene--sulfonic acid-and l-hydroxynaphthalene in 200 parts of water, the evaporated water being made good. The Whole is cooled to 40-45 C., the new chromiferous dyestufi is completely dissolved by the addition'of caustic soda lye. The solution is filtered'from impurities and the filtrate is neutralized with dilute'acid and evaporated to dryness in a vacuum. The'dyestuff thus obtained is a violet-black powder of bronze appearance which dissolves in water to 'a blackblue solution, in dilute sodium carbonate solution to a blackish violet solution, in dilute caustic soda lye to a blackish red-violet solution andnin concentrated sulfuric acid toa greenishblue-black solution. It dyes wool in a bath acid with organic acid and sulfuric acid greenish navy blue tints.

Example 8 In 200 parts of water there are dissolved 15.1

parts of the chromiferousdyestufi obtained by chroming in common inJan acid medium equal parts of the dyestufi from diazotized l-amino-Z- hydroxynaphthalene-4-sulfonic acid and 2,-hydroxynaphthalene and the dyestuff from diazotized 1-amino-2-hydroXynaphthalene-4-sulfonic W acid and l-hydroxynaphthaleneand 6.35,.partsof sodium a-naphthalenesulfonate This solution is heated together with a solution of 10.65 parts of the dyestufi from diazotized 1-amino-2-hydroxy-' naphthalene--sulfonic acid and l-hydroxynaphthalene-BL-sulfamide in 200 parts of water: for several hours, the evaporated water being made good. The whole is now cooled to 40-45" 0., the

newchromiierous dyestutf is completely dissolved by addition of caustic soda lye. The solution is filtered from impurities and the filtrate neutralized with dilute acid and evaporated to dryness in a vacuum The dyestuff thus obtained is a violetblack powder, soluble in water and dilute sodium carbonate solution to a blue solution, in dilute caustic soda lye to a violet solution and in concentrated sulfuric-acid toa greenish blue-black solution. It dyes wool in a bath a'cidwith organic "acid and sulfuric acid pure blue tints.

Example 9 I l V I In imparts of water are dissolved-33-parts -of thalene and the dyestufi from diazotized 1- ;uum. The dyestufi thus obtained is a violetamino-2-hydroxynaphthalene-4-sulfonicacid and ll-hydroxynaphthalene and 5.2 parts of common salt. Thissolution isheated Witha solution of 19.8 parts of the dyestufi of 'theformula from diazotized 1-amino-4-sulfobenZene-2-carboxylic acid and l-(2'-methyl-4'-sulfo)-phenyl- 3-methyl-5 pyrazolone in 400 parts of water for several hours the evaporated water. being made good. The whole is cooled to 40-45 0., the new chromiferous dyestuff is dissolved completely by the addition of caustic soda lye. The solution is filtered from impurities and the filtrate is neutralized with diluteacid and evaporated in a vacuum to dryness. The dyestuff thus obtained is a black powder soluble in water and in dilute so-, dium carbonate solution to olive-black solutions, in dilute caustic soda solution to a blackish redvioletsolution and in concentrated sulfuric acid to .a yellowish green solution. It dyes wool in a bath acid with organic acid and sulfuric acid dark green tints.

' Example 10 In 800 parts of water are dissolved 31.9 parts of the chromiferous dyestuitobtained by chroming in common in' acid medium equal parts of the dyestufi from diazotized l-amino-Z-hydroxynaphthalene-4sulfonic. acid and 2.-hydroxynaphthalene and the dyestuff from diazotized 1- amino-2 hydroxynaphthalene 4- sulfonic acid a COOH Cl obtainable by coupling diazotized 4-chloro-2- 'aminod-phenol-G-sulfonic acid with benzoyl acetic ortho-carboxylic acid, 13 parts of sodium lactate are added to the solution and the whole is boiled for several hours in a reflux apparatus. When no more unchromed dyestufi is to be detected the solution is filtered from impurities and evaporated in a vacuum to dryness. There is obtained a new chromiferous dyestuff in the form of a black powder Which'dissolves' in water and in dilute sodium carbonate solution to a blackish blue solution, in dilute caustic soda lye to a blackish violet solution and in concentrated sulfuric acid to a blue-black solution. It dyes wool in a bath acid with organic acid and sulfuric acid blue tints of good fastness.

The following table contains further examples of the dyestuffs obtainable in accordance with this inventionz Chromium compound of the azo-dyestulf Azo-dyestufi No 7 Alkali-forming Dyeimzjon I i a metal salt wool Parts Formula Parts Formula I 1 38,5 13.2 Sodiumformate-.- Black-blue.

N01 sou:

2 33 17.6 OH Sodium be'nzene- Navy blue.

. Y I sulfonate 3 15,1 do 16.6 OH FiOgNHa Sodiuma-naphtha- Do. lene sulfonate 4 44 -.-.do 7.1 Magnesium sul- Dark green.

COOH Cl 66 lo 28.6 N,=N Ammonium aee- Reddish l tate navy blue. OH new Chromium compoundM'theazodyestufi. .lhfidy e tufl' 1 a I l No LAIkali-Iorming Dyeing on i V metal salt ,wool

Parts Parts Formula a 36 14.05 15.4 Sodium acetate ue Navy blue.

SOaH

What we claim is: e

1. Process for the manufacture of chrorniferous azo-dyestufis from mixtures'of chromed azodyestufis and chromable azo-dyestufis which mixtures contain at least one idyestufi of the general formula:

, of an azo-dyestuif qf the general formula wherein the hydroxyland the azo-group are in ortho-position to each other, and wherein 1L equalsl'to 3, and R is a naphthol radical; con sisting in boiling these mixtures for at least'four hours arr aqueous medium and in the absence of free acids with"alkali-forming metal salts which are at themost slightly hydrolyzed in aqueous solution. '7 ff Y 31 "Process forthe manufacture of chromiferous a'zo dyestuffs from mixtures of chromed azodyestuffs and chromablegazo-dyestufis which mixtures contain at least one chromium compound of an azo-dyestufi of the general formula wherein the hydroxyland the azo-group are in ortho-position to each other, and wherein R is a naphthol radical, consisting in boiling these mixiures foratleastffour hours in aqueous-me- .diu rriland in the absence of free acids with alkaliforming-metalsalts which are at the most sliig htly .hydw f yezsdnr u us o i 7 V Process for -the manuifacture of chromiferous azo-dyestufis from mixtures of chromedazo -dyc-r stuffs and chromable azo-dyestufis which mixtures contain a chromiumcombound of an azodyestuff of the general formula" ortho-position to -each. otherfland wherein 'R is .a naphthol radicaL-consisting in boilingithese mixtures forat-leastlfour hours in an aqueous medium and in the absencelofafree .acids w ith alkali-forming metal salts which rare-at the most slightly hydrolyzed in aqueous, solution. 1 5. Process for'the manufacture of ichromiferous azo-dyestufis from mixtures :of chromed azodyestuffs and chromable "am-dyestuffs; which mixtures contain at least one dyestufi of the "1: soul 1 wherein Rfis-a 'naphthol radical, consisting in boiling thesemixturesifor at least four hours in an aqueous medium and inthe absence" of free acids with alkali-forming metal salts which are at the most slightly. hydrolyzedin aqueous solution.' J Y 1 wiir 6. Process for the manufacture of chromiferous azo-dyestuffs from mixtures of chromed azodyestuffs and rchromable azo-dyestufls which mixtures contain a chromium compound of the azo-dyestufi of theformula e if consisting in boiling these mixtures for at least four hours in an aqueous medium andinthe absenceofifreeacids with alkali-forming metal salts which are atthe most slightly hydrolyzed in aqueous solution. 1

V T -Process Qforthe manufacture of azo-dyestufis and chr'omable azo-dyestufis winch mixtures contain :a chromiumc compound of the azo-dyestuff of the'formula as well as the same unchromed azo-dyestuff, con

sisting in boiling these mixtures for at least four hours in an aqueous medium and injthe absence of free acids with alkali-forming metal salts which, are; at the most ;slightly hydrolyzed in aqueous solution. i

8. Process for the manufacture of chromiferous azo-dyestufis from mixtures of chromed azo 'dyistuffs and chromabl ai'o' dyestuffs which mixtures contain a chromium compound of the as well as-Lt'he same unchromed aiao -dyestufl, consisting *in boiling these mixtures 011.31; ieast our hours in an :aqueous' medium and-in the absence of free acids with aniaikali forming metal .salt ofan aliphatic acid;

- 9. Process for the manufactured chrom:iferous azo-dyestuifs from mixtures .of'chmomed azodyestuffs Y and ohrocmable azo-v-dyestufis which mixtures contain a; chromium compound of the azo dyestufi of'the formula as well as the same unch-romed azoV-dyestufi, consisting. in boiling these mixtures for atrleast four hours' in' an aqueous medium and in the absence of free acids with sodium acetate; p

10. Chromiferou's azo-dyestufis, obtained from mixtures oi? chromed azo-dyestuifs'and chromable azo-dyestufis, which mixtures contain at wherein the hydroxyl and the azo -group are in orthopositiori .to each ,qther', aridawherein n equals 1 to 3, and R'is anaphthQI :radical, by boiling these mixtures for at; least four hours in an aqueousmedium and in the ahse'nce of free acids with alkali-forming metal salts which are at the most slightly hydrolyzedin aqueous solu- ''tion, "which products represent dark coloredwoo-l powders v asi l'y soluble in'water and yarioustintsof very'goodfastr'ress. v 1-1. Chromiferous azo-dy'est1:ri'fs; obtained mixtures of chromed azo-cdyge'stufisand bhromabie' a'z-o -,dyestuifs which mixtures eent'a-m at from ammo

-least one chromium -compou-ndof stud of the general-formula an Y azo-dye- .ortho-position to leach otheryand wherein 1:. equals 1 to 3; and R is a naphthol radical; by

' boiling these mixtures for at least four hours in an aqueous medium and in the absence of free acids with alkali-forming metal salts which are at the most slightly hydrolyzed in aqueous solutiOIil, which products r'eprSent dark colored powders easily solublewin mater and dyeing wool various tints of very good fastness;

12. Chromiferous azo-dyestufis, obtained from mixtures of chromed azo-dyestuifs and chrom- Vahle .azo-idyestufis, which mixtures. contain at least one chromium compound of.-an .azondyestufi of the general ,formula. v I

wherein the hydroxy-l-- and thefazo-group are in V ortho-position toeach other, and wherein R is a naphthol radical, by boiling these mixtures for at least four hoursrin-an aqueous medium and in the absence of free acids with alkali-forming metal salts which are at the most slightly hydrolyzedin aqueous solution, which products represent .darkcolored powders .easily isoluble in water and .dyeingwool various (tints of Very good iastnessic Y z '13.. Chromifrous vazo-dyestufis, obtained from mixtures of chromed azo-dyestu'ffs and achromable azoedyestufis, c which mixtures contain a chromiurnicompoundof an azodyestu-fi of the ene e -o' mula F l wherein the hydro yI- and azo-group are in ortho-position to each-other, and wherein R is a naphthol radical, by boiling these mixtures for at leastviour ,hoursin aniaqueous and in the absence of :free acids with alkili-forming metalsalts which sweat the most slightly hydrolyzed aqueous solution, which products repnescnt dark. colored powders easily soluble in water and idyeing'wool various tints of very good fastness. j

1i. Chromiferousazo-dyestufis, obtained from mixtures of chromed azo-dyestuffs and chromable ,azo-dyestufis,- which mixtures contain a chromiumcompound of an azo-dyestufi .of the e er l mrmu 1 V lIT=N-B v I v i vS0313: v

wherein R is a naphthol radical, by boilingthese mixtures sf orsat least four hours in anaqueous medium and in the absence of free acids with alkali-iorming metal salts'which are at the most slightly hydrolyzed in aqueous solution, which products represent dark colored powders easily soluble in water and dyeing wool various tints of very good fastness.

15. Chromiferous azo-dyestufis, obtained from 7 mixtures of chromed azo-dyestufis and chromable azo-dyestuffs, which mixtures contain a chromium compound of the azo-dyestufi of the V formula OH HO- SOsH by boiling these mixtures for at least four hours in an aqueous medium and in the absence of free acids with alkali-forming metal salts which are at the most slightly hydrolyzed in aqueous solution, which products represent dark colored powders easily soluble in'water and dyeing wool Various tints of very good fastness. r g

16. Chromiferous az0-dyestuffs, obtained from mixtures of chromed azo-dyestufis and chromable azo-dyestuffs, which mixtures contain a chromium compound of the azo-dyestufl ot the formula SOs as well as the same unchromed azo dyestufi,

by boiling these mixtures for at least four hours in an aqueous medium and. in the absence of free acids with alkali-forming metal salts which are at the most slightly hydrolyzed in aqueous solution, which products represent dark colored powders easily soluble in'water and dyeing wool blue to navy blue tints of very good fastness,

particularly to rubbing, and excellent color in the artificial light.

formula v 17. Chromiferous azo-dyestufis; obtained from mixtures of chromedaz'o-dyestufis and chromable azo-dyestufis, which mixtures contain a chromium compound of the azo-dyestufl of the formula scan as well as the same unchromed azo-dyestufi, by V boiling these mixtures for at least four hours in an aqueous medium and in .the absence of free acids with an alkali-forming metal salt of an I aliphatic acid, which products represent dark a 1 I p v SOSH V t as well as the same unchromed azo-dyestufi, by boiling these mixtures for at least four hoursin an aqueous medium and in the absence of free 4 acids with sodium acetate, which products represent dark colored powders easily soluble in water and dyeing wool blue to navy blue tints of very good fastness, particularly to rubbing, and excellent color in the artificial light.

FRITZ STRAUB. V 'I-IERMANN SCHNEIDER. 

